N-(t-butyl ester-PEG6)-N-bis(PEG6-amine) is a PEG reagent that can easily react with activated NHS esters or carboxylic acid in the presence of EDC or HATU. The t-butyl group can be deprotected under acidic conditions. The hydrophilic PEG spacers increase the compounds water solubility in aqueous media. Reagent grade, for research use only.